Adult learning is a lifelong process whereby knowledge is formed through the transformation of adults' experience. Research on online adult learning has been on the rise in recent years, thanks to the innovative opportunities provided to adults by digital technologies. Online communities of practice (OCOPs) a one of such opportunities, which offer the potential to bring geographically dispersed adult learners together through a common interest. Despite an increased growth in the use of OCOPs by adults in various professional sectors, there is still a lack of understanding of the characteristics of online adult learning in OCOPs, and the facilitators and hinderers influencing engagement in these communities. This paper presents a comprehensive synthesis of research literature on online adult learning in OCOPs to understand its characteristics and what may facilitate or hinder adults' engagement in these communities. A review has been conducted using a systematic, rigorous and standard procedure, aiming to summarise and synthesise existing research on the topic and to provide analytical criticism. In total, thirty-seven studies were included in this review. Findings revealed that members of OCOPs are independent, experience-centred, problem-centred, self-motivated, goal-oriented, and lifelong learners with the purpose to achieve professional outcomes. Moreover, the results revealed how the engagement of adults in OCOPs could lead to improving learning processes. Findings also showed that the level of engagement is influenced by aging, fatigue caused by a busy life, resistance process due to learning new technologies, lack of personal evolution, interactive learning settings, motivation, self-regulation and competition factors. This study revealed facilitators and hinderers of engagement in OCOPs. The study extended andragogy to digital environments and contributes to the theory by making sense of characteristic of adult learning in OCOPs.

Practitioner notes

What is already known about this topic

• The importance of lifelong learning for adults in the digital era has been stressed by past studies.
• Digital technologies have offered new opportunities for professional adults to continuously develop their skills and knowledge.
• Online communities of practice can facilitate self-directed and individual-centred learning.

What this paper adds

• Enhances our understanding of online adult learners as lifelong learners taking advantage of OCOPs for professional and personal development.
• Provides a systematic literature review (SLR) of recent studies on online adult learners' characteristics.
• Presents facilitators and hinderers of adults' engagement in OCOPs.
• Makes recommendations on future research and practice into lifelong learning in the digital era.

Implications for practice and/or policy

• There is a need to reframe the way lifelong learning via OCOPs is defined, to account for adults' needs more effectively, where individuals are better engaged to share their experiences that are valuable to them and connects them with their peers to build sustainable online communities.